The present invention relates to the field of vehicle security, and more particularly, to a vehicle security system and door lock interface module therefor.
Vehicle security systems are widely used to perform various security-related vehicle functions, such as switching between armed and disarmed modes responsive to remote transmitter. An example of such a vehicle security system is disclosed in U.S. Pat. No. 5,654,688, assigned to the assignee of the present invention, wherein a number of remote transmitters capable of operating the controller is displayed to the user so that the user can be sure that no unauthorized transmitters have been learned to into the system. U.S. Pat. No. 6,037,859 also assigned to the assignee of the present invention, discloses a vehicle security system wherein the receiver portion may be mounted in the windshield area to provide an increased operating range from the remote transmitter. Various switches and indicators are also provided on the window portion for user convenience.
Another function commonly performed by a vehicle security system is the remote operation of the vehicle door locks also based upon signals from the user-carried remote transmitter, for example. More particularly, many vehicles include power door locks including at least one door lock switch, a door lock control unit responsive to the switches and that, in turn, operates one or more door lock motors. One type of power door lock system includes a single wire extending from the door lock switch to the door lock control unit. A predetermined voltage, e.g. ground or positive twelve volts, for example, is coupled from the door lock switch to a first terminal of a respective lock or unlock resistance to generate a corresponding voltage signal at the door lock controller to thereby lock or unlock the door locks.
Unfortunately, different manufacturers and different vehicles within a manufacturer""s vehicle line typically have different lock and unlock resistances even for the single wire schemes. Accordingly, installation of an after-market security system typically includes first determining the lock and unlock resistances associated with the door lock switch. Once determined, respective fixed resistors matching these resistances are provided to interface one or more switching relays of an interface device to the door lock circuit. Of course, maintaining an inventory of different resistors is cumbersome, and the steps to determine, select, and install the resistors, may be time consuming and subject to error. Of course, there are also other schemes for operating the door locks, such as, a multi-wire negative pulse scheme, a multi-wire positive pulse door lock scheme, and reversal rest at a predetermined voltage (ground or positive) scheme.
In view of the foregoing background, it is therefore an object of the present invention to provide a vehicle security system and associated methods that permit ready interface to different door lock circuits of different vehicles.
This and other objects, features and advantages in accordance with the present invention are provided by a vehicle security system for a vehicle having a door lock circuit including at least one door lock switch and at least one door lock controller responsive thereto, and wherein one or more variable resistors are provided in an interface module. More particularly, the vehicle security system may include a security controller for selectively operating the at least one door lock controller, and a multi-vehicle compatible interface module for interfacing the security controller to the door lock circuit of a given vehicle from among a plurality of different vehicles. The door lock circuit of a vehicle can include, for example, a single-wire door lock circuit having at least one of a lock resistance and an unlock resistance to be selectively connected in series with a voltage reference to operate the door lock controller. In some embodiments, the multi-vehicle compatible interface module may include a circuit board, a first variable resistor, and a second variable resistor, both carried by the circuit board. The first and second variable resistors can be set to match the respective lock and unlock resistances of the door lock switch.
The door lock circuit can be a positive single-wire door lock circuit or a negative single-wire door lock circuit. Accordingly, the multi-vehicle compatible interface module can include circuitry for interfacing to the respective positive or negative single-wire door lock circuit.
The interface module can also include a severable wire loop extending outwardly from the circuit board and having opposing ends connected in parallel with one of the first and second variable resistors. The severable wire loop connected in parallel thus defines a selectable bypass jumper. The first and second variable resistors can each be provided by multi-turn variable resistor, such as operable over a range of about fifteen to twenty turns, for example.
According to another feature of the invention, the multi-vehicle compatible interface module can also be compatible with other door lock schemes in addition to the single-wire schemes. For example, the interface module can include circuitry carried by the circuit board for interfacing with a negative or positive pulse multi-wire door lock circuit, or with the reversal rest at a predetermined voltage door lock circuit.
A method aspect of the invention is for interfacing a vehicle security controller to a vehicle door lock circuit including at least one of a lock resistance and an unlock resistance to be selectively connected in series with a voltage reference by a door lock switch to thereby operate a door lock controller. The method may comprise connecting a multi-vehicle compatible interface module between the security controller and the door lock circuit. The multi-vehicle compatible interface module may include at least one variable resistor and associated circuitry. The method may further include setting the at least one variable resistor of the multi-vehicle compatible interface module to match at least one of the lock resistance and unlock resistance of the vehicle door lock circuit.